Mv. Jimenez et al., Competitive reaction pathways in the addition of phenylacetylene to diamidonaphthalene-bridged diiridium complexes, ORGANOMETAL, 18(7), 1999, pp. 1125-1136
The oxidative addition of phenylacetylene to the monohydrido diiridium comp
lex [Ir-2(mu-1,8-(NH)(2)naphth)H(CO)(2)(PiPr(3))(2)] (CF3SO3) (2) and the d
iiridium(II) species [Ir-2(mu-1,8-(NH)(2)-naphth)(CF3SO3)(2)(CO)(2)(PiPr(3)
)(2)] (3) has been studied. The kinetic product of the addition to 2 is the
dihydridoalkynyl complex [Ir-2(mu-1,8-(NH)(2)naphth)mu-C=CPh)H-2(CO)(2)(Pi
Pr(3))(2)](CF3SO3) (4), in which the alkynyl ligand bridges the iridium ato
ms in a mu,eta(1):eta(2)-coordination mode. Compound 4 isomerizes in aceton
e solution tot give the hydride-bridged complex [Ir-2(mu-1,8-(NH)(2)naphth)
(mu-H)H(C=CPh)(CO)(2)(PiPr(3))(2)](CF3SO3) (5), in which both the alkynyl a
nd the terminal hydride ligands are in a trans position with respect to the
bridging hydride. The reaction of phenylacetylene with 3 gives different k
inetic products depending on the solvent used. In CH2Cl2, the diiridium(III
) derivative [Ir-2(mu-1,8-(NH)(2)naphth)H(C=CPh)(CO)(2)(PiPr(3))(2)](CF3SO3
)(2) (6) is obtained. On heating these CH2Cl2 solutions, 6 isomerizes into
the vinylidene-bridged complex [Ir-2(mu-1,8-(NH)(2)naphth)mu-C=CHPh)(CF3SO3
)(2)(CO)(2)(PiPr(3))(2)]-(7), which has been characterized by X-ray diffrac
tion. The triflate ligands of 7 can be substituted by acetonitrile ligands
to give the dicationic compound [Ir-2(mu-1,8-(NH)(2)naphth)-(mu-C=CHPh)(NCC
H3)(2)(CO)(2)(PiPr(3))(2)](CF3SO3)(2) (8). With acetone as the reaction sol
vent, the addition of phenylacetylene to 3 affords deprotonated compounds o
f formula [Ir-2(mu-1,8-(NH)(2)-naphth)(C=CPh)(CO)(2)(PiPr(3))(2)](CF3SO3) (
9 and 10). The thermally stable isomer 10 can be protonated to give 7 but c
an also react with an excess of phenylacetylene to give the neutral diiridi
um(II) species [Ir-2(mu-1,8-(NH)(2)naphth)(C=CPh)(2)(CO)(2)(PiPr(3))(2)] (1
1), which is the isolable product of the reaction of 3 with an excess of ph
enylacetylene in acetone. When this latter reaction is carried out in aceto
ne/H2O as solvent, the acylalkynyl diiridium(II) complex [Ir-2(mu-1,8-(NH)(
2)naphth)(C=CPh)(C(O)CH2Ph)(CO)(2)(PiPr(3))(2)] (12) is the major reaction
product. The molecular structure of 12 was determined by X-ray diffraction.